Tuesday, 22 April 2008

Risk of brain damage from anti-cancer chemotherapy drug

"A chemotherapy drug used to treat thousands of cancer patients could cause serious brain damage with effects that are felt for years, research suggests today.

The drug, 5-fluorouracil (5-FU), which is one of the most commonly prescribed anti-cancer medicines, is used for tumours of the breast, ovary, colon, stomach, skin, pancreas and bladder.

However, tests showed that it destroys brain cells and could be responsible for side effects known as "chemo brain", which include memory loss, poor concentration, and in more extreme cases, seizures, impaired vision and dementia. Most chemotherapy drugs are toxic to some degree, often noticeable because of hair loss and nausea. They can affect healthy as well as cancerous cells.

Doctors have urged patients not to abandon the drug as it is an effective weapon against cancer.

The findings, reported today in the Journal of Biology, could explain some of the neurological side effects associated with chemotherapy.

Eight out of 10 breast cancer patients reported some form of mental impairment after chemotherapy. Studies have found that up to a fifth had problems that lasted for years. The research, from the University of Rochester Medical Centre in New York state, showed that 5-FU attacks the cells in the brain that play a crucial role in the central nervous system.

They produce myelin, the fatty material that enables signals between cells to be transmitted rapidly and efficiently.

However, myelin deteriorates quickly and has to be constantly replenished.

Without a healthy population of these cells to renew it, normal communication between brain cells is disrupted. Scans of cancer patients with mental difficulties have shown evidence of loss of myelin leading to the loss of nerve fibres making up the "white matter" in the brain.

The researchers treated mice with doses of 5-FU comparable with those given to cancer patients and also exposed brain cells in dishes to the drug.

Months after exposure, the key cells both in the cell cultures and the brains of mice were undergoing extensive damage.

The disruption was so severe that after six months the cells had virtually disappeared from the mice.

Dr Mark Noble, of the medical centre, said: "It is clear that, in some patients, chemotherapy appears to trigger a degenerative condition in the central nervous system."

You can lower your risk of developing most cancers by avoiding salt and salty food.